Philosophy may have begun when people started thinking about the beginning—or the arché, as the pre-Socratics teach us—but it is equally probable that such reflections were inspired by the realization that things have not just a beginning, but also an end. The classic example of a syllogism and therefore of an unshakeable argument is “All men are mortal, Socrates is a man, therefore Socrates is mortal.” That Socrates is mortal is the result of an inference, but that all men are mortal is a premise you cannot argue with. In the course of history, many “incontrovertible truths” (that the sun revolves around the Earth, that there is such a thing as spontaneous generation, that the philosophers’ stone exists) have been called into doubt, but not the fact that men are mortal. At most, the faithful believe that one man rose again, but before that happened, he had to die first.